This database is a compilation of published and some unpublished isotopic and fission track age determinations in central Colorado. The compiled area extends from the Wyoming border to the New Mexico border and from approximately the longitude of Denver on the east to Gunnison on the west. Data from outside the study area were included to provide information on regional age. Data for the tephrochronology of Pleistocene volcanic ash, Carbon-14, Pb-alpha common-lead, and U-Pb determinations on uranium ore minerals have been excluded.
This compilation was concentrated in the area of the Central Colorado Assessment Project and will be used to develop a geologic framework for the area as part of the compilation of a 1:100,000 geologic map for the study area. Data from outside the study area were included to provide information on regional age relationships and their compilation is, therefore, not as exhaustive,
The USGS conducted the Central Colorado Assessment Project (CCAP) from 2003 to 2008 to provide federal, state, and local land management entities geoscience information to address issues related to urbanization of the Colorado Front Range Urban Corridor. Rapid population growth along the Front Range and in the CCAP region, which encompasses about 20,800 square miles (53,800 km2) of central Colorado between the New Mexico and Wyoming borders (37 - 41 degrees north latitude), and from west of Denver to east of Vail Colorado (approximately 104.8 - 106.625 degrees west longitude), has caused tremendous demand for natural resources and has created challenging land-management issues related to the wilderness/urban interface expansion. Regional CCAP data, including geologic, geochemical, geophysical and remote sensing data, were compiled to assess the availability of mineral resources; the geo-environmental effects of historical mining and wildfires; geologic controls on groundwater resources; and hazards such as landslides and flooding.
publication date
Data have been checked to ensure the accuracy. If any errors are detected, please notify the originating office. The U.S. Geological Survey strongly recommends that careful attention be paid to the metadata file associated with these data. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and (or) contained herein. Acknowledgement of the U.S. Geological Survey would be appreciated in products derived from these data. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this Federal Geographic Data Committee-compliant metadata file is intended to document the data set in nonproprietary form, as well as in ArcGIS format, this metadata file may include some ArcGIS-specific terminology.
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Spatial data sets supporting the Central Colorado Assessment Project (CCAP) were developed by the U.S. Geological Survey Central Mineral Resources Team (CMRT) and the Crustal Imaging and Characterization Team (CICT) in cooperation with the U.S. Geological Survey Earth Surface Processes Team (ESP), the Colorado Geological Survey (CGS), the Rocky Mountain Region U.S. Department of Agriculture-Forest Service (USDA-FS) and the National Park Service (NPS).
Analytical accuracy, if reported, is found in the "Age_Uncert" field in the data table. Other author generated information relative to data accuracy are found in the "Comments" field
A site is a single geographic location where geochronology information has been obtained and documented in published and some unpublished communications
Of the available published material, we think we estimate that we have compiled at least 90% of the information from 1956 to 2009
Locational accuracy is limited to information in the original reports. Estimation of accuracy is sometimes found in the "Comments" field. In some cases published locations were modified to put the sample in the appropriate geologic unit.
Locational accuracy is limited to information in the original reports. Estimation of accuracy is sometimes found in the "Comments" field. In some cases published locations were modified to put the sample in the appropriate geologic unit.
Source information for data compilation.
Data were compiled from published and some unpublished sources. This database includes data from Wilson and Bryant (2006) for the Fort Collins, Estes Park, Denver West, and Bailey 1:100,000 quadrangles in the northern and central Front Range. These data were supplemented with more recent age determinations and some of their locations were updated. using additional infomration
Metadata imported.
Internal feature number.
ESRI
Feature geometry.
ESRI
Lithology of sample
Metadata author
Formal or informal rock unit name or geographic area
Metadata author
Published field or laboratory number where available
Metadata author
Longitude in decimal degrees
Metadata author
Latitude in decimal degrees
Metadata author
USGS ½ x 1 degree topographic quadrangle name
Metadata author
USGS 7-1/2-minute topographic quadrangle name
Metadata author
Geochronology method
Metadata author
fission track
Meatadata author
Potassium/Argon
Meatadata author
Neodymium-Samarium
Meatadata author
Rubidium-Strontium
Meatadata author
Uranium-Lead
Meatadata author
40Argon/39Argon
Meatadata author
Type of material analyzed
Metadata author
Geochronologic age, in millions of years (Ma)
Metadata author
Analytical precision
Metadata author
Age as reported
Metadata author
Short form of determination reference
Metadata author
Comments on the age determination
Metadata author
Additional discussions of data are provided in the accompanying text, DS489.pdf
The point features in this dataset contain 16 attribute fields. The fields "FID" and "Shape" are automatically generated and populated by the software. The remaining 14 attributes fields were added by the authors to summarize geochronology of the samples.
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Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made by the U.S. Geological Survey regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty. No responsibility is assumed by the U.S. Geological Survey in the use of these data.
Box 25046, Mail Stop 973